Listagem por temas:

Escolhendo um título você terá acesso ao arquivo original em Post-Script.

COB85 COMPARAÇÃO DOS SISTEMAS DE COLHEITA MANUAL E MECANIZADO ATRAVÉS DA AVALIAÇÃO ENERGÉTICA E FINANCEIRA PARA CULTURA DE CANA-DE-AÇÚCAR (Saccharum spp.) / COMPARISON OF MANUAL AND MECHANICAL HARVESTING OF SUGAR CANE (SACCHARUM SPP.) BY ENERGETIC AND FINANCIAL EVALUATION

Maria Márcia Pereira Sartori & Alcides Lopes Leão

Departamento de Ciências Ambientais, Faculdade de Ciências Agronômicas -UNESP- Botucatu, S.P, Brasil

CEP 18.600-000 Botucatu, S.P, Brasil - E-mail: jrsartori@surfnet.com.br

The sugar cane crop represents an enormous potential for energy, due to its phytomass excess left on the fields, which is burned as a way to ease the manual harvesting. Most of this energy could be utilized if changes are made in the harvesting practice, such as using mechanical harvesting instead of manual.

The present study had the objective to show the viability of substituting manual harvesting with burning in the fields, by mechanical harvesting (green cane), with a better energy recovery from its residues and net income. For the calculations we used the gross calorific value and the Brazilian currency (Real), at an exchange rate of approximately R$1=US$1.

The results showed that this change in harvesting procedure is economical and energetically more efficient. For manual harvesting the energy consumption was found to be 39,725.96 Mcal/ha (166,292.87 x 10³ J/ha) at a cost of R$113.62/ha. For mechanical harvesting the energy consumption was 19,063.32 Mcal/ha (9,799.06 x 10³ J/ha) at R$61.98/ha. With the utilization of the residues it was obtained 312,218.4 (1306,946.22 x 10³) and 435,263.2 (1822,011.76 x 10³) Mcal/ha (J/ha), 1,304.90 and 1,574.70 R$/ha, respectively. The social aspects of relocation of the manual labor is not considered in this paper.

Keywords: cana-de-açúcar, biomassa, colheita, mão-de-obra, bagaço, mecanização.

Keywords: sugar cane; bagasse; mechanical-harvesting; manual-harvesting; bionergy; biomass

COB97 NUMERICAL SIMULATION OF THERMAL STORAGE ON ENCAPSULATED PHASE CHANGE MATERIALS

Carlos Eduardo L. Nóbrega e Sergio L. Braga

Departamento de Engenharia Mecânica – PUC-Rio, 22453-900 – Rio de Janeiro – RJ - Brasil

Thermal storage on encapsulated phase change materials (pcm) is under consideration. The phase change (solidification/melting) process is approximated by a quasi-stationary model, which is solved together with the one-dimensional transport equation. Results are shown by the evolution of the non-dimensional outlet temperature through non-dimensional time.

Keywords: Thermal storage, latent heat, encapsulated phase change material.

COB760 NUMERICAL SIMULATION OF THERMAL STORAGE ON ENCAPSULATED PHASE CHANGE MATERIALS

Carlos Eduardo Leme Nóbrega and Sergio Leal Braga

Departamento de Engenharia Mecânica

Pontifícia Univesidade Católica do Rio de Janeiro -Rua Marquês de São Vicente , 225 , 22453-900- Rio de Janeiro caduln@centroin.com.br and slbraga@mec.puc-rio.br

Thermal storage on encapsulated phase change materials (pcm) is under consideration. The phase change (solidification/melting) process is approximated by a quasi-stationary model, which is solved together with the one-dimensional transport equation. Results are shown by the evolution of the non-dimensional outlet temperature through non-dimensional time.

Keywords: Thermal storage, latent heat, encapsulated phase change material.

COB826 ESTIMATIVA DO POTENCIAL DE CONSERVAÇÃO DE ENERGIA EM INTALAÇÕES DE BOMBEAMENTO/ ESTIMATE OF THE ENERGY POTENTIAL CONSERVATION IN PUMPING SYSTEMS

Edson da Costa Bortoni

DEE/UNESP - Universidade Estadual Paulista, CEP: 12500-000 Guaratinguetá - SP – Brasil - E-mail:bortoni@feg.unesp.br

Geraldo Lúcio Tiago Filho & Benedito Cláudio da Silva

DME/LHPCH/EFEI - Escola Federal de Engenharia de Itajubá, 37500-000 Itajubá - MG – Brasil - E-mail: tiago@iem.rmg.br

It’s unusual that a pumping sistem works with just one fixed condition of flow and pressure. The processes that work with centrifugal pumps have, in general, a variable consumption and in the case of necessity of changing the flow, in normal systems, is necessary to act in the control valve, which will change the sistem curve because of the introduction of adctional friction losses in the instalation. Meanwhile, it will cause a unnecessary energy consumption. Another way to change the flow of a pumping system is through the variation of the pump speed, using a variable speed driver that has less consumption of energy and presents a series of advantages over the throtting valve, due the agreement bettwen the pump caracteristics and the instalation caracteristics and the optimization of the project point. Based in this considerations, this work presents a methodology that permits to estimate the real saving energy potential in centrifugal pumps drived by constant speed electrical motors. It’s done through the determination and analysis of the grafic caracteristics, providing in this way, data for a viability economic analysis with less riscs and uncertainty.

Keywords: Conservação de energia, bombas centrífugas, instalações de bombeamento / Energy conservation, centrifugal pumps, pumping systems.